Electric Fields,Circuits Electric Fields; Emf,Currents,Potential Difference and Multiloop Circuits

1
Electric Fields,Circuits Electric Fields
Emf,Currents,Potential Difference and Multiloop
Circuits

• Lecture 21
• Thursday 1 April 2004

2
Coulombs Law
3
Recall the Coulomb Force Problem on Two Charges
What is the force on q0 due to q if q 2 C , qo
3 C and the distance between them is 3 meters?
How about if qo 3 C ? How about if qo 1.5
C? .. Calculating the force exerted by q on any
given charge you might place at the location of
qo gets repetitive. The only thing that changes
is the value of qo.
4
The Electric Field

• We define the electric field associated with a
  charge or charge distribution to be the
  electrostatic force exerted per unit of charge on
  which the force acts.
• If we know E, the force, F, on any charge, qo,
  is then given by
• We can calculate E once and then get F for any
  charge easily.

5
The Electric Field

• From a point charge q, the force on q0 is,
• Then, at q0s location, the field associated with
  q is
• Field is a vector. The direction is away from a
  positive q and toward a negative q. It is also
  always in the direction of F on a positive charge.

6
(No Transcript)
7
Example
8
Example
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13

14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)